Phex before 2.8.6 allows remote attackers to cause a denial of service (application hang) by initiating multiple chat requests to a single user and then logging off.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26124
http://www.vupen.com/english/advisories/2006/1560
http://sourceforge.net/project/shownotes.php?release_id=412751